NIRISS: create example anomaly page

[stscijgbot-jwql]

Issue JWQL-207 was created on JIRA by Bryan Hilbert:

From the user survey:
The NIRISS team asked for the creation of an example anomaly page.
We'll need input from the NIRISS team to explain and point out examples of each type of anomaly. Also, if the anomalies are documented on JDox, we may want to simply link to those pages.